• Journal of the Korean Ceramic Society
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• v.36 no.4
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• pp.333-342
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• 1999

This research was performed to investigate how the basic glaze change affected colour development at high temperature with a stable colorant (spinel structure CoAl2O4 pigment) The compounded pigment which is widely used for porcelain was also tested for the basic glazes adaptability. The data from the test were recorded in a computer data-base program. Therefore could be easily used in the study related with a pottery field. CoO : Al2O3 system spinel pigment of barium glaze lime glaze zinc glaze lead glaze and talc glaze were chosen for this study. The colors of Cobalt blue bright blue, blue purple were seen at the wave lengths of 455-480nm at the firing temperature of 1250$^{\circ}C$. Stable color were obtained from lime glaze bar-ium glaze zinc glaze. All the information in the database were used to examine all the possible result of the test in the study of porcelain. When the test results database were examined in all temperature ranges the lack of adhesion with the pigment occurred at the temperature of 1150$^{\circ}C$. The lack of adhesion is seen due to vaporization of the lead glaze.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.598-602
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• 2010

When metal oxides are added into crystalline glaze, colors of glaze and crystals are similar as colorants generally. But the case of NiO in zinc crystalline glaze is different from general color development. When NiO is added to zinc crystalline glaze it can develop two or three colors. The active use of color development mechanism by adding NiO to the zinc crystalline glaze to control color of the base glaze and crystal with stability is investigated. This report is expected to contribute to the ceramic industry in improving application of zinc crystalline glaze. For the experiment of NiO, the quantity of NiO additives is changed to the base glaze for the most adequate formation of willemite crystal from previous research and firing condition: temperature increasing speed $5^{\circ}C/min$, holding 1 h at $1270^{\circ}C$, annealing speed $3^{\circ}C/min$ till $1170^{\circ}C$, holding 2 h at $1170^{\circ}C$ then naturally annealed. The samples are characterized by X-ray diffraction (XRD), UV-vis, and Micro-Raman. The result of the procedure as follows; Ni substitutes for Zn ion then glaze develops blue willemite crystals, as if cobalt is used, on brown glaze base. When NiO quantity is increased to over 5 wt%, willemite size is decreased, and the density of the crystal is increased, at the same time $Ni_2SiO_4$ (olivine) phase, the second phase, has been developed. The excessive NiO is reacted with silicate in the glass then developed green $Ni_2SiO_4$ (olivine), and quantity of $Ni_2SiO_4$ (olivine) is increased as quantity of willemite is decreased. It is proved to create three colors, blue, brown and green by controlling the quantity of NiO to the zinc crystalline glaze and it will improve the multiple use of colors to the ceramic design.

• Economic and Environmental Geology
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• v.57 no.3
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• pp.343-352
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• 2024

Composition analysis and lead isotope ratio analysis were conducted to determine the coloring machanism on lead glaze used in Gyeongbokgung Palace and the provenance of the lead used as a flux. 31 blue tiles were classified into green, blue, and yellow. The chemical analysis of lead glazes on the blue tiles revealed that Pb, Si, and Cu were the main components, and trace amounts of Fe, Ca, Mg, and Al were detected. The Cu content was high in blue lead glaze, while Cu was not detected in yellow or brown lead glaze which instead had high Fe content. Therefore, it was found that lead was used as a flux and copper oxide as a coloring agent in the production of lead glaze. In addition, the lead isotope ratios of the lead glaze used in the blue tiles of Gyeongbokgung palace were plotted in zone 3 on the distribution map of lead isotope ratios on the Korean Peninsula, which includes Chungcheong-do and Jeolla-do. It is presumed that the flux for the lead glaze was sourced from galena found in these regions. The lead isotope ratios of the green glaze from the Three Kingdoms and Unified Silla period were mostly located outside the Korean Peninsula, showing that the provenance of lead had changed. In particular, the lead isotope ratios of the green glaze from the Three Kingdoms and Unified Silla period suggest exchange with neighboring countries. Also the lead isotope ratios of the green glazes from the same temple are different, so it is believed that they were made at different times or in different workshops.

• Korean Journal of Materials Research
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• v.23 no.5
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• pp.271-275
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• 2013

Cobalt (Co) compounds have been used for centuries to impart rich blue color to glass, glazes and ceramics. Cobalt monoxide (CoO), an oxide of Co, is an inorganic compound that has long been used as a coloring agent in the ceramic industry. Unlike other coloring agents, CoO can be used to develop colors other than blue, and several factors such as its concentration in the glaze and firing condition have been suggested as possible mechanisms. For example, CoO produces a typical blue color called "cobalt blue" at very low concentrations such as 1 wt% in both oxidation and reduction firing conditions; a higher concentration of CoO (5 wt%) develops a darker blue color under the same firing conditions. Interestingly, CoO also develops a purple color at high concentrations above 10 wt%. In this study, we examined the applicability and mechanism of a novel purple glaze containing cobalt(II, III) oxide, one of the well characterized cobalt oxides. Experimental results show that an Augite crystal isoform (Augite-Fe/Co) in which Fe was replaced with Co is the main component contributing to the formation of the purple color. Based on these results, we developed a glaze using chemically synthesized Augite-Fe/Co crystal as a color pigment. Purple color glaze was successfully developed by the addition of 6~15 wt% of $Co_3O_4$ to magnesia lime.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.5
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• pp.183-189
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• 2014

This study was conducted to study the influence of Co and Fe on the color of glaze and diopside crystals in the diopside crystal glaze empirically produced and used by ceramic artists, in case of adding $Co_3O_4$ and $Fe_2O_3$. As a result, the color of glaze was blue when $Co_3O_4$ was added to the diopside crystal glaze and the diopside crystals appeared pastel violet with Co included. When $Fe_2O_3$ was added to the diopside crystal glaze, the color of glaze appeared brown and the color of diopside crystals was goldenrod with Fe included. The crystals precipitated on the surface of diopside consisted of diopside crystals and diopside precursors. With longer retention time, the amount of diopside precursors decreased and the amount of diopside crystals increased. Also, Co was more easily included by the diopside crystals than Fe was and crystallizability of dispside was improved in case of including Co. Including Fe lowered peak intensity of properties and partially dissolved the diopside crystals.

• Journal of the Korean Ceramic Society
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• v.35 no.4
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• pp.378-384
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• 1998

We investigated the possibility of systemizing data for the colour gradation of classical ceramics by build-ing program and D-basing each data information in pottery field that has been fall behind in forming data be-cause of many variable and lacking of data system. In this study we manufactured $CoAl_2O_4$ stain that has stable spinel structure at high temperature and then mixed base glaze with stain for the additive per-centage of 0.5 , 1, 5, 10, 15 wt% In thie colouring of Lime base glaze with the wide ranged melting tem-perature the colour development of cobalt-blue sintered at $1250^{\circ}C$ is better than that of $1150^{\circ}C$ $1350^{\circ}C$ The experimental conditions and data are D-based simulated programming of computer. The result of -based data appeared to be more smoothed fusion-adherence in the Matt glaze range of Lime base glaze, The variation of colouring is not found when additive content of glaze is more than 5 wt% and the stable colour development of stain was shown at the content that RO, $R_2O$ percentage is high (the content that R2O3 per-centage is low)

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.548-553
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• 2009

This study is on the application of ceramic body and art glaze by using coal ash according to each wt%. Body color was turned red and dark as increasing coal ash contents in the body and art glaze because of the effect of noncombustible carbon in $Fe_2O_3$ and coal ash. Not only pore and black core were generated but also absorptance and shrinkage were increased as increasing coal ash contents. The glaze of coal ash 20 wt% showed blue absorption band, turned red band as increasing coal ash contents, $Al_2O_3\;to\;SiO_2$ ratio got lower and became mat because glaze is estranged from $Al_2O_3\;to\;SiO_2$ mol ratio 1:10 of transparent glaze as increasing coal ash contents. Glaze showed unstable dissolving condition in the more coal ash contents.

• Journal of the Korean Ceramic Society
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• v.12 no.1
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• pp.29-36
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• 1975

This study was conducted to research the formation, color development and application for colored glazes of the spinel solid solutions of the green pigment. On specimens prepared by calcining the oxide and basic carbonate mixture at 1250℃ for 1.5 hour, the x-ray analysis, measurement of reflectance and the test of their stabiality as a glaze pigment were carried out. The results are summarized as follows 1) Each sample is composed of single spinel and not of mixture of spinel. 2) Formation of continuous soild solution, except for a few instances, pertaining to Vegard's law was confirmed by means of the x-ray analysis. 3) The more difference between absorption and reflectance lies, the lighter colors are. When the absorption occurs at the high-reflectance, the excitation purity becomes low. On the contrary when the absorption takes place at the low-reflectance, the excitation purity becomes low. On the contrary when the absorption takes place at the low-reflectance, the excitation purity is higher. 4) Colors obtained in the CdO-MgO-Cr2O3-Al2O3 system, as the amounts of Al3+ increased, change from green through brown to pink, and the absorption peak shifts towards violet region. 5) An increase in Co2+ in the CoO-MgO-Cr2O3-Al2O3 system, changes the color from blue green to dark blue. The excitation purity is higher, and the absorption peak shifts toward regions. 6) Colors are green in the NiO-MgO-Cr2O3 and CdO-MgO-Cr2O3 systems in general, but in the ZnO-MgO-Cr2O3 system brillant hue is not obtained. 70 According to the results of the colored glaze test, the spinels turn outto be stable as brilliant glaze pigment in the calcium-magnesia glaze.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.603-607
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• 2010

Turquoise blue pigment of Vanadium-zircon blue (DCMA number 14-42-2), which was already commercialized, was stable to be reproduced but insufficient to give strong blue. However, it possible to obtain more intense blue by partially substituting cobalt ions into the willemite($Zn_2SiO_4$) lattice classified into DCMA number 7-10-2 for blue ceramic pigment. By the composition of willemite $Co_xZn_{2-x}SiO_4$(X=0.01, 0.03, 0.05, 0.07, 0.09 mole), this study used reagent grade zinc oxide, cobalt oxide and silicon dioxide as starting materials, carrying out the synthesis with solid reaction method by adding $H_3BO_3$ as a mineralizer. The firing temperature was between $1200^{\circ}C$ and $1400^{\circ}C$. The characteristics of synthesized pigment were analyzed by X-ray diffraction, Raman spectroscopy and SEM and the characteristics of color tones were analyzed by UV-Vis spectroscopy and CIE-$L^*a^*b^*$ measurement. As a result, the optimal composition was $Zn_{1.95}Co_{0.05}$ with 1wt% of $H_3BO_3$ as a mineralizer and firing condition was $1350^{\circ}C$/3 h. $L^*a^*b^*$ value was 29.25, 41.03, -59.93 for on glaze pigment and 37.03, 36.41, -60.03 for under glaze pigment.

• 보존과학연구
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• s.29
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• pp.221-238
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• 2008

Roofing tiles are very important archaeological artifacts which show science, architecture of that time, as well as information about the culture. It has been studied by many researchers steadily, but only focusing on archaeological, art historical and architectural study, so it is very difficult to find natural science research. Gyeongbokgung's roofing tiles were excavated from the ruins of same site, however glaze, body colour and shape of tiles are very diverse with the naked eye. Through natural science research which analyze the chemical composition and physical characteristics of roofing tiles's body and glaze examine the physical and chemical characteristics of each roofing tiles. the result of analazed roofing tiles is following. when roofing tiles were classified by 전암대자율 and chromaticity, each group has part of some matches. When you compare with green gazed traditional brick's glaze of Silla period, Gyeongbokgung roofing tiles have more $Al_2O_3$ and less PbO than Silla period's. We can see the technology of increasing firing temperature is better. and glaze colour depends on content of $Fe_2O_3$ and CuO. A lot of CuO tend to be more blue.